Method for lubricating contacting frictional surfaces in equipment handling a viscous solution

Claim 1

IN THE TRANSPORTATION OF A VISCOUS MASS COMPRISING A NORMALLY SOLID HIGH ACETYL CELLULOSE ESTER AND A SOLVENT THEREFOR THROUGH A RELATIVELY RESTRICTED PASSAGE BY MEANS OF A PROPELLING DEVICE HAVING MOVING PARTS WITH CONTRACTING FRICTIONAL SURFACES HOUSED IN A REGION ACCESSIBLE TO NORMALLY LIMITED QUANTITIES OF SAID MASS AND FROM WHICH NORMALLY LIMITED QUANTITIES OF A LUBRICANT MIGHT REACH SAID MASS, AN IMPROVED METHOD FOR FACILITATING THE PROPULSION OF SAID MASS COMPRISING CONTINUOUSLY MAINTAINING IN CONTACT WITH SAID SURFACES AS THE ONLY LUBRICANT THEREFOR A NORMALLY LIQUID, RELATIVELY HIGH-BOILING, SUBSTANTIALLY NONVOLATILE STABLE NON-HYDROCARBON SOLVENT FOR SAID NORMALLY SOLID CELLULOSE ESTER COMPATIBLE WITH THE SOLVENT CONTAINED IN THE VISCOUS MASS.